Aluminum storage disc

Abstract

A process for the metal plating of aluminum comprising the steps of electrolytically anodizing the surface of the aluminum, immersing the anodized aluminum into an electrolytic plating solution and initiating deposition by passing a current through the solution for a time sufficient to form a layer of metal over the aluminum. The process is especially useful for the formation of aluminum storage discs where the electrolytic metal is a single layer of a ferromagnetic metal.

We claim: 
     
       1. A metal plated aluminum storage disc comprising an aluminum storage disc substrate, an electrically anodized oxide layer over at least a surface of said aluminum storage disc substrate, said anodized oxide layer having cracks propogating throughout its surface which cracks define discrete oxide islands separated from each other by said cracks, and a layer of electrolytically deposited ferromagnetic metal over said discrete oxide islands, said ferromagnetic metal being columnar in structure conforming in size and shape to said oxide islands and extending upwards from said islands. 
     
     
       2. The aluminum storage disk of claim 1 where the anodized oxide layer is formed at a current density of at least 8 amps per square foot. 
     
     
       3. The aluminum storage disk of claim 2 where the electrolyte is a sulfuric acid solution in a concentration of from ten to forty percent by volume and the current density varies between about 12 and 20 amps per square foot. 
     
     
       4. The aluminum storage disc of claim 2 characterized by the ferromagnetic metal layer being a single metal layer. 
     
     
       5. The aluminum storage disc of claim 2 where the metal layer is selected from the group of cobalt and colbalt-nickel alloys. 
     
     
       6. The aluminum storage disc of claim 5 where the metal layer is cobalt. 
     
     
       7. The aluminum storage disc of claim 5 overcoated with a second metal.